In various present handheld electronic devices and communication equipments (such as mobile phones, personal digital assistants, and palmtop computers, etc), a notebook computer is an important item among these electronic information products. As the annual demand of the information market keeps growing, and various information products are developed and advanced rapidly, the research and development concept for related electronic products tends to be designed with a high-frequency and high-speed data processing mode and comes with light, thin, short, and compact features. To minimize the size of the information products, the chips inside the information device are miniaturized gradually, but such miniaturization does not imply reducing the functions of the products. On the contrary, the add-on values and functions of these electronic products are improved according to consumer requirements.
Since the circuit design of computers at early stage is simpler, its application programs are fewer, and its operating speed is slower, therefore there exists no problem in the related model designs, electronic components and layouts. However, manufacturers have to add many electronic components and chips in a smaller main system now, and thus design engineers have to fit many components in very limited space and cannot afford wasting any space. Thus, finding a way to further reduce the volume of each electronic component and each hardware component in the very narrow and small space and add extra functions and components to satisfy consumer requirements has become a big issue to major electronic manufacturers and also has become a key factor to determine the success of a particular manufacturer.
Referring to FIGS. 1 and 2 for the prior art direction key structure installed on a notebook computer, the direction key structure is disposed between the surface of a casing and a circuit board 1, and the direction key structure comprises a first pressing member 2 and two second pressing members 3. The two second pressing members 3 are arranged separately on both sides of the first pressing member 2, and a surface of the pressing member 2, 3 faces exterior of the casing to allow users to press the pressing member 2, 3, and another surface faces the circuit board 1. The first pressing member 2 includes a groove 20, a plurality of protruding pillars 200, and two suspending arms 22. The groove 20 is disposed on another surface of the first pressing member 2, and an end of the protruding pillar 200 is disposed on the bottom surface of the groove 20 and arranged in the up, down, left, and right sides and disposed on both sides and both ends adjacent to the first pressing member 2, and another end faces a plurality of contact points 10 on the circuit board 1. An end of each of the two suspending arms 22 is disposed separately on another surface of the connecting position of the first pressing member 2, and another end of each suspending arm 22 is extended out of both sides of the first pressing member 2 and keeps a first interval A from another surface of the two second pressing members 3 and a second interval B from the circuit board 1. An end of each of the two suspending arms 22 is coupled to an internal surface of the casing, such that the elasticity of the two suspending arms 22 drives another end of the protruding pillar 200 to press the contact points 10, when the first pressing member 2 is pressed separately in the up, down, left, and right sides, so as to input instructions for moving the cursor in different directions for the notebook computer.
In FIGS. 1 and 2, the second pressing member 3 includes another groove 30, another protruding pillar 300, and a supporting stand 32, wherein the other groove 30 is disposed on another surface of the second pressing member 3, and an end of the other protruding pillar 300 is disposed on the bottom surface of the other groove 30, and another end of the other protruding pillar 30 is extended into a hollow space of the suspending arm 22, and another end of the other protruding pillar 300 faces a plurality of other contact points 12 on the circuit board 1, and the other contact points 12 maintain the second interval B apart, and an end of the supporting stand 32 is coupled to a side of the second pressing member 3, and another end is fixed into the casing. The supporting stand 32 on the surface of the second pressing member 3 faces the exterior of the casing, such that if the second pressing member 3 is pressed, another end of the other protruding pillar 300 will press the other contact points 12 for controlling the notebook computer.
Although the direction key structure is installed by a stacking method according to the foregoing structure, the first interval A must be greater than the second interval B in order to prevent another surface of the second pressing member 3 from touching the suspending arm 22, when another surface of the second pressing member 3 is pressed, so as to prevent the first pressing member 2 from being pushed by the second pressing member 3 that will press the contact points 10. However, such arrangement may greatly increase the thickness of the direction key structure, as shown in FIG. 2, which includes the thicknesses of the second pressing member 3, the first interval A, the thickness of the suspending arm 22, and the second interval B. As a result, the space in the notebook computer has to accommodate the thickness of the direction key structure, not only wasting the internal space of a notebook computer, but also going against the trend of the light, thin, short, and compact design of the present electronic devices, which further increases the level of difficulty for miniaturizing the notebook computer.